The invention relates to a sheet delivery device for flexible sheet material, especially paper, with at least one deflection wheel which has at least one receiving slot which is located essentially tangentially, a sheet feed guide which discharges into at least one receiving slot when it is in a receiving position and a sheet delivery stop in the area of the deflection wheel which is opposite a receiving position, the wheel running in a recess of the sheet delivery stop and the latter lying in the sheet delivery position at least on one side of the receiving slot.
One typical sheet delivery device is known from DE 23 09 075 A1. In this sheet delivery device an even stack is produced. But it is often necessary for an offset to be formed in the stack in the tray after a certain number of sheets. This can be used for example to better acquire the total number of sheets. This is especially important when different sheets, which belong together, are being continuously printed. This is often the case in electrophotographic printing machines. Then it is necessary for one job to be separated from another by this offset.
Therefore the object of the invention is to develop a sheet delivery device of the type such that an offset in the delivered stack can be easily produced.
This invention is done in that on one shaft there are at least two deflection wheels which have receiving slots in identical positions, and that the one shaft can be inclined relative to the sheet transport direction of the sheet feed guide. By this invention, with a simple development it becomes possible to produce an offset at any time without interrupting the sheet delivery. In this way it is possible for example to separate one job from another even if the jobs each have a different number of sheets. Furthermore it is also possible to use the invention is a smaller correcting range to control the delivery position of the sheets, to correct deviations and thus to neatly stack sheets which belong together on top of one another.
The function of the invention is for the sheet material to run into the receiving slots and after 90xc2x0 rotation to be inclined by the same angle as the shaft with the deflection wheels. If at this point the deflection wheels continue to move and in doing so guide the sheet material to the sheet delivery stop, rotation by roughly 180xc2x0 takes place so that the sheet is inclined by twice the angle as the shaft. If one part of the stack is to be offset relative to another, the shaft is inclined from its perpendicular position to the transport direction preferably once in one direction and once in the other direction so that the offset is an angular offset of one part of the stack relative to the other part of the stack which is four times the incline of the shaft. Of course the shaft could also be aligned once perpendicular to the transport direction and could be inclined for the next part of the stack.
Feasibly, the deflection wheels are made such that they each have two receiving slots offset by 180xc2x0. Thus the delivery position of one of the receiving slots is identical to the receiving position of the receiving slots offset by 180xc2x0. In this way the deflection wheels can pick up a new sheet with each revolution and can deliver the previous sheet.
When a sheet is fed, it must be ensured that the receiving slots of the two deflection wheels are in the receiving position. This can be done by there being a plurality of receiving slots on the deflection wheels and their having an opening so large that in each position of the deflection wheels there are receiving slots in the receiving position. This is the proposal of DE 23 09 075 A1. But it is also possible to ensure by other means that with sheet feed the receiving slots are in the receiving position. For example, one proposal calls for there to be a braking device which stops the deflection wheels in at least one receiving position. For example, there can be a cam disk against which an element presses, and the element must overcome elevations of the cam disk in the receiving positions.
To achieve the motion of the deflection wheels which is necessary for sheet delivery, it can be provided that the deflection wheels are made with respect to their weight and the shaft is made with respect to its bearing such that the deflection wheels can be driven by the feed of the sheet material.
One alternative calls for there to be a drive for the deflection wheels. Then, instead of the braking device it can be provided that the drive is made such that it stops the deflection wheels in the receiving positions. For example, a stepping motor can be used for this purpose.
So that the drive can drive the shaft even when it is in an inclined position, it is possible to place it directly on the shaft so that it keeps up with the inclined position. But alternatively it can also be provided that the drive is located in the machine housing and transmission to the shaft takes place. If for example the shaft is swiveled around a swiveling axis, it can be provided that the swiveling axis is made as a hollow shaft in which there is a power transmission shaft.
Preferably the receiving slots are made V-shaped at the start of the slot. In this way it is ensured that the sheet material is reliably picked up and the receiving slot can be made so narrow after the start of the slot that the sheet material is securely held.
In order to achieve a neat angular offset of the sheet material, the slots should be made as narrow as possible. To prevent rebound by striking the end of the slot it is suggested that on at least one receiving slot there is a braking device for the sheet material which reduces its speed before striking the slot end such that no rebounding occurs on the stops. There are various possibilities for this braking device. One proposal calls for the braking device being made as elastic brackets which are located in the area of the receiving slots and which have friction relative to the sheet material. For example, rubber brackets can be used.
One feasible embodiment of the aforementioned development calls for the brackets to be movable into the insertion path of the sheet material. In this way it is possible to move them in the receiving position into the insertion path and in the delivery position to remove them from the path so that sheet delivery is not hindered. It is therefore proposed that the braking device be released for the sheet material in the sheet delivery position. The braking device can pass into the engagement and release position for example by an eccentrically supported weight which conveys the brackets in the receiving position into the insertion path and removes them again in the delivery position from the area of the receiving slots.
One development calls for the sheet delivery stop to be adjustable with respect to its angular position. Then an adjustment can be made according to the inclination of the shaft. But it can also be provided that the angular position of the sheet delivery stop is coupled to the angular position of the shaft such that the inclination of the sheet delivery stop always corresponds to twice the angle of inclination of the shaft. In this way the sheet delivery stop automatically has the correct position.
One alternative embodiment calls for the shaft to be inclinable from the perpendicular to the transport direction in both directions by a predetermined angle and for the sheet delivery stop to be made V-shaped, each leg of the V having twice the angle as the angle predetermined for the shaft. In this way the angular offset in delivery is dictated, but adjustment of the sheet delivery stop is saved, since one leg of the V-shaped formation always has the correct position to one of the predetermined angles.
A corresponding embodiment of the sheet feed guide ensures that the positioning of the sheet material in the receiving slots is always exact.
For example, there can be at least one transport roller for the sheet material on the sheet feed guide. But preferably there are two interacting transport rollers.